Door closure means for industrial ovens and the like



June 28, 1966 G. J. BREGMAN 3,257,976

DooR cLosUEE MEANS EoR 'INDUSTRIAL ovENs AND THE LIKE 3 Sheets-Sheet l Filed April 21. 1964 INVENTOR. GEORGE rl BREGMAN June 28, 1966 G. J. BREGMAN 3,257,976

DOOR CLOSURE MEANS FOR INDUSTRIAL OVENS AND THE' LIKE ATTORNEYS June z8, 1966 G. J. BRE-GMM 3,257,976

DOOR CLOSURE MEANS FOR INDUSTRIAL OVENS AND THE LIKE Filed April 21. 1964 3 Sheets-Sheet 5 L M i Boido xNvENTOR.

ATTORNEYS UnitedStates Patent O 3,257,976 DOOR CLOSURE MEANS FOR INDUSTRIAL OVENS AND lTHE LIKE George J. Bregrnan, Shaker Heights, Ohio, assignor to The Foundry Equipment Company, Cleveland, Ohio, a corporation of Ohio Filed Apr. 21, 1964, Ser. No. 361,411-

Claims. (Cl. 11G-173) The present invention -relates generally, as indicated, to a door closure means for industrial ovens and the like and, more particularly, to door closure means for releasably urging the doors of an oven into tight sealing engagement with the .adjacent wall surfaces of the oven when the doors are in the closed position.

In large industrial ovens of the type used to dry large sand :molds and the like, explosive mixtures may become trapped in the oven, especially where the oven is of the direct fuel lired type in which fuel and combustion products are directed into the oven during the drying process. Should these explosive mixtures accumulate and suddenly be ignited, an explosion might occur which could cause considerable damage to -the oven unless some means is provided immediately to relieve the excessive pressure caused by such explosion. To protect adequately ovens of this type from damage due to such explosions, it has gene-rally been considered desirable to provide approximately one square foot of relief area on the oven for each 15 cubic feet of space within such oven.

, In the past, relief areas have been formed by providing loose panels in the ceiling of the oven which readily yield under .the influence of high pressure. This type of relief panels has particularly lbeen used in long conveyor ovens through which articles are continuously transported by means 'of an endless conveyor system, for example. Further, in ovens of the type having large vertical doors,

- simple door latching means have been used which are effective to allow the entire door to act as a relief panel should there be an explosion within the oven. However, there Ihas been a problem in sutliciently tightly clamping the panels or doors in place to prevent the escape of 3,257,976 Patented June 28, 1966 ice cam the doors into tight sealing engagement with the adjacent wall surfaces of the oven when the doors are in the closed position.

Another object is to provide rollers adjacent the top and bottom o f the side edges of the doors for engaging the cam surface of such resiliently pivotably mounted latches.

Yet another. object is to provide adjustable stopscrews on `the latches for-determining the normal position of such cam surfaces as well as determining the extent to which the latches may be rocked about their pivots.

Another object is to provide pivotally mounted latches on the walls of the oven adjacent the openings therein with spring means which are effective resiliently to maintain the latches in their normal position when the latches are normally disposed, but which are also effective to fumes while at the same time avoiding too much resistance to .the force exerted against the door if an explosion should take place within the oven.

It is highly desirable that the fumes within the oven be precluded from escaping, not only from a safety standpoint, but because the escaping hot air through the cracks between the panels or doors and the adjacent oven walls will tend to warp such panels or doors and t-hus substantially increase the ineiectiveness ofthe seal, the result being a considerable amount of heat loss.

It is therefore a principal object of this invention to provide the doors of an industrial oven and the like with closure means which are effective to clamp the doors against the adjacent oven wall surfaces to prevent the escape of gases therefrom, while at the same time assuring that the doors will be allowed to move outwardly away from the oven walls with a minimum amount of resistance to relieve and preclude an excessive build-up of pressure within the oven should an explosion occur therewithin.

It is another object to provide an oven the doors of which are tightly but yieldingly clamped to the adjacent wall surfaces of the oven when the doors are in the closed position. A

A further object is to provide a plurality of resiliently supported latches on the wall of an oven adjacent the openings therein which are operative yieldingly to clamp the oven doors in the closed position.

Still another object is to provide a cam surface on each of such -resiliently mounted latches which is elfective to maintain the latches in the open position when moved to such open position.

Still another. object is to so'position such resiliently 'mounted latches on the walls of an oven adjacent the opening therein that whenthe cam surfaces of the latches are engaged by rollers on the doors, a clamping force is exerted by the latches against the 'door -to force the same into tight engagement with the adjacent walls of lthe oven. Other objects and advantages of the present invention .will become apparent as the following description proceeds.v

'llo the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but yone ofthe various ways in which the principle of the invention may be employed.

In said annexed drawings:

lFIG. 1 is a vertical section of an industrial oven the doors of which are adapted to be clamped to the adjacent oven Walls by a preferred form of door closure means constructed in accordance with the present invention;

FIG. 2 is a somewhat enlarged fragmentary end elevation of the yoven of FIG. l as viewed from the left end thereof; v

FIG. 3 is a fragmentary side elevation, partially broken away, of the oven of FIG. '2 as viewed from the right side thereof; v

FIG. 4 is an enlarged detailed view of the lower door closure means of FIG. 2;

FIG. 5 is an enlarged fragmentary horizontal section of the oven taken on the plane of the line 5 5 of FIG. 2;

FIG. 6 is an enlarged detailed view of the lower door closure means of lFIG. 3; and

FIG. 7 is a side elevation view similar to that of FIG. 3, but showing the door forced away from the oven opening and the door closure means in their open position.

Referring now more particularly to the drawings, and irst of all to FIG. l, there is illustrated therein an industrial -car-type mold oven 1 supported on a loor 2 of the plant in which the oven is located. In each end of the oven 1, the openings 3 may be `sealed by lowering doors 6 movable vertically in angle guides 7 secured -to the end walls of the oven 1 adjacent the openings 3 therein and extending upwardly along such end walls a considerable distance above the roof or ceiling 8 of the oven.

Since the construction of both doors 6 is the'same, the

same reference numerals have been used to designate like parts. Moreover, since the operation of each of the doors 6 is identical, the operation 'of only the door 6 disposed adjacent the left end of the oven 1 as viewed in FIG. 1 will be described in detail.

The vertical door angle guides 7 are supported by suitable braces 12 extending from an I-beam 13 preferably supported above the ceiling S of the oven 1. Secured to the upper end of the angle guides 7 there is a cross frame 14 on which are mounted a plurality of laterally spaced idler pulleys 1S over which there are trained a corresponding number of cables 16, one end of which is attached` to a top ange 17 of the door 6. Each cable 16 is further Itrained over a drive pulley 1S the shaft of which is adapted to be driven by an electric motor (not shown) for raising and lowering the door 6 into position.

l The number and size of such cables 16 used is dependent on kthe weight of the door 6. In the particular type of oven shown, the doors are generally approximately 20 feet wide, 12 feet high, and weigh about 5,000 pounds. Because of this great weight, a counter-weight 19 is desirably secured to the other end of the cables 16, thus substantially reducing the load on the drive pulley motor during raising and lowering of the door 6. The left end door 6 of FIG. 1 is shown in the lowered or closed position while the right end door is shown in the raised or open position.

To dry molds placed in the oven 1, both of the doors 6 are closed and heated air is forced into a ceiling duct which extends over a substantial portion of the inner surface of the ceiling 8. From the ceiling duct 25 the heated air is directed into the oven 1 through a plurality of holes or ports 26 in the bottom wall 27 of the duct 25. The air is heated in a heater 28 preferably mounted on the top of the oven ceiling S. The heater 28 consists of a conventional gas and oil fired burner the llame of which is directed into a casing 29 through which airis circulated by means of a fan and directed into the ceiling duct 25 via a conduit 30 communicating with an opening 31 in the ceiling 8.

To recirculate air from the oven, a pair of return or collector ducts are mounted on the inner side wall of the oven 1 adjacent each end thereof. Secured to the lower ends of the ducts 35 there is a horizontally extending duct 36 running substantially the entire length of the oven, such duct 36 being provided with a plurality of openings 37 through which the air may pass. The upper ends of the ducts 35 are connected to an annular chamber 38 defined by the adjacent walls of the oven 1 and ceiling duct 25. The chamber 38 is in turn connected to the heating chamber or casing 29 via suitable ducts 39 communicating with the chamber 38 through an opening 40 in the oven ceiling 8;

For more ecient operation of the oven, it is desirable continuously and completely to exhaust a certain quantity of air therefrom, as by directing a limited amount of air through an external exhaust duct 41 communicating with the annular chamber 38 through an opening 42 in the oven ceiling 8 and leading to an exhaust stack 43.

Since the detailed construction and operation of the oven per se forms no part of the present invention, no further discussion of the same is thought to be necessary. However, for a more detailed description of the construction and operation of a similar type industrial oven, reference may be had to Patent No. 2,988,351, issued to Charles H. Barnett and Richard E. Teagle on June 13, 1961.

As previously indicated, it is quite important in constructing ovens of this nature, where fuel and combustion products may accumulate in the ovens, to provide relief areas for allowing the immediate escape of excess pressure which may develop in the ovens due to an explosion therein. Moreover, it is also important that hot air and other gases within the ovens not be allowed to escape through cracks which may exist around the relief areas, since not only are these gases dangerous from a safety standpoint, but also escaping hot air through these cracks will tend to warp the relief areas. To solve the abovenoted problems, the oven l'shown and described herein is provided with a plurality of unique door closures or latch assemblies 50 which are not only operative tightly to clamp the doors 6 against the adjacent wall surfaces of the oven 1 to preclude the escape of hot air and gases therefrom during normal operation of the oven, but yet are operative quickly to release the doors should there be an explosion in the oven so that excessive pressure can escape therefrom.

As is readily apparent from FIGS. 2 and 3 of the drawings, a pair of vertically spaced latch assemblies 50 is mounted on each of the door angle lguides 7, the spacing being such that one of the latch assemblies 50 is disposed adjacent each corner of the oven doors 6 when the doors are in the closed position. Since the structure and operation of cach of the latch assemblies 50 is the same, only one of such latch assemblies will be described in detail.

Referring now to FIGS. 4-6, each latch assembly 50 preferably includes an irregularly shaped thin metal bar member 51 pivotally mounted to the longitudinally extending leg 52 of the door angle guide 7 as by means of a nut and bolt assembly 53, the nut 54 of which is received in a recess 55 in the bar member 51. Secured to the bar member 5,1 is a cam plate 56, such cam plate 56 extending inwardly toward the adjacent edge of the door 6 a slight distance beyond the bar member 51 to dene a flat cam surface 57.` Each of the cam surfaces 57 is adapted normally to be maintained in the inclined position shown in solid lines in FIG. 6, for example, so that when the door 6 is lowered into the closed position, rollers 60 mounted adjacent the top and bottom corners of the door will engage the cam surfaces 57 in such a manner that the door 6 will be cammed tightly shut when it reaches its lowermost position. As clearly shown in FIGS. 4 and 5, each roller 60 is' preferably attached to the outer surface of the door 6 by means of an angle bracket 61, one leg 62 of which is bolted to the door 6 and the other leg 63 of which supports a roller shaft 64 about which the roller 60 is adapted to rotate.

The cam plate 56 and bar member 51 are yieldingly maintained in the solid line position of FIG'. 6 by means of a spring assembly 68 comprising a .rod member 69 and compression spring 74. One end of the rod member 69 is formed in the shape of a ball 70 for universal movement in a socket 71 in the bottom of the bar member 51, while the other end of the rod member extends through an aperture 72 in a pressure angle 73 secured to the leg 52 of the door angle guide 7. The compression spring 74 is disposed around the rod member 69 for yieldingly urging the rod member 69 toward the bar member 51. The ends of the spring 74 are confined between an adjustable tension nut 75 threadedly engaging the one end of the rod member 69 and a bushing 76 slidably disposed on the other end of such rod member and seated in the aperture 72 in the pressure angle 73. An aperture 77 is provided adjacent such other end of the rod member 69 through which a pin (not shown) may be inserted for precluding the complete removal of the rod member 69 from the aperture 72 .in the pressure angle 73 except when desired.

This disposition of the spring assembly 68 with respect to the bar member 51 in its normal position is such thatthe force F exerted by the spring assembly 68 against the bar member 51 acts in a direction slightly to the left of the pivot 53 as viewed in FIG. 6, thus tending to rotate the bar member 51 in a clockwise direction. This force F exerted by such spring assembly 68 against the bar member 51 may be varied by adjusting the tension nut 75 on the rod member 69 to vary the effective length of the spring 74. Further, the length of the moment arm R through which the .force F acts tending to rotate the bar member 51 may be varied as by providing the pressure angle 73 with a pair of slots S0 for limited adjustment of 5. the pressure angle. plished by loosening nut and bolt assemblies 81 extending through such slots 80 and sliding the pressure angle 73 either to the right or left as viewed in FIG. 6 to the extent desired.

To limit the extent to which the bar member 51 and cam plate 56 may be rotated in the clockwise direction as aforesaid, an adjustable stopper bolt 82 preferably projects from a surface of the bar member for engagement with the other leg 83 of the door angle guide 7. Of course, the length of the stopper bolt 82 may be adjusted to vary the position on the leg 83 of the angle guide 7 at which the bolt 82 will engage the same and thus vary the normal angular disposition of the bar member 51 and cam plate 56.

It can now be seen that when the rollers 60 on the door 6 engage their respective cam plates 56 of the latch assemblies 50 as the door is lowered into the closed position, sealer angles 84, which are mounted on the side walls of the door 6 and extend axially rearwardly therefrom, will be cammed into tight pressure engagement with the adjacent sur-faces of the door angle guides 7 mounted on the adjacent oven end wall. Further, a sealer angle 85 (FIGS. 3 and 7) mounted on the top edge of the door 6 Will be cammed into tight pressure engagement with the adjacent end wall of the oven 1 while the bottom edge of the door 6 will tightly engage a sill 86 of the oven 1. Suitable vertically extending angle guides 87 may also be provided ion the door angle guides 7 for limiting the transverse movement of the door 6 as it is moved in the vertical direction.

The disposition of the rollers 60 on the door 6 and the location of the latch assemblies 50 onthe door angle guides 7 are such 'that the effective Weight of the door (i.e., that weight which is not counterweighted; preferably about 300 pounds) is supported by the cam plates.

56, the weight being such that there is a slight rotational movement of the cam plates 56 in a counterclockwise direction as viewed in FIG. 6 prior to engagement of the bottom edge of the door 6 with the sill 86 as aforesaid. Thus, the weight of the doors 6 as well as the force F of the spring assemblies 68 exerted against the bar mem- Such adjustment would be'accombers 51 tends to urge the door 6 and thus the sealer angles l 84 and 85 into tight engagement with the adjacent oven surfaces.

However, when this clamping force is exceeded as by a force created by a sudden explosion within the interior of the oven 1, the doors 6 will be forced outwardly against the cam plates 56 to cause such cam plates 56 and bar members 51 to rotate in a counterclockwise direction as viewed in FIG. 6. Thus, the door 6 will be allowed to move in the direction of the explosive force exerted thereagainst With a minimum amount of resistance so that the excessive pressure created by the explosion can escape from the oven. It should be noted that when the cam plates 56 are moved suiciently such that the force F exerted on the bar members Srl by the spring assemblies 68 acts in a direction to the right of the pivots 53 as viewed in FIG. 6, the spring assemblies 68 will urge the cam plates 56 and bar members 51 in a counterclockwise direction'to the phantom line position, and thus no further resisting force will be exerted by the cam plates 56 againstthe rollers 60 and door 6. The extent to which the, cam plates 56 and bar members 51 may be rotated in the counterclockwise direction is desirably limited by an adjustable stopper bolt 90 projecting outwardly from the bar members 51, such stopper bolt being similar in construction and operation to the stopper bolt 82 previously described. With the cam plates 56 in the extreme outer or counterclockwise position, the door 6 may move freely outwardly in the manner shown in solid lines i-n FIG. 7 and in phantom lines in FIGS. 5 and 6 to relieve excess pressure as aforesaid. After relieving such pressure, the weight of the door 6 will cause the same to swing inwardly to the solid line position of FIGS.

3, 5, and 6, for example. Then, the operator need only rotate the cam plates 56 in a clockwise direction against the force of the spring assemblies 68 until the spring assemblies once again act in a direction to the left of the pivot 53, at which time the cam plates 56 will be forced .by the spring assemblies .in `a clockwise direction into clamping engagement with the rollers 60 on the door 6 to force the door into sealing engagement with the oven 1.

From the yabove discussion, it should now be readily apparent that the relatively simple door closure means of the present invention is not only effective to clamp the door of an industrial oven and the like against the adjacent Wall surfaces thereof to prevent the escape of gases therefrom, but also readily permits outward movement of the door away from the oven when excessive pressure is established therewithin.

Other modes of applying the principles of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore, particularly point out and distinctly claim as my invention:

1. In combination with an industrial oven having an v.end wall with a door opening therein Iand a door sill, a door for closing such opening, door angle guides secured to said end wall adjacent said door opening, rollers mounted'on said door, sealer angles mounted on the side walls of said door, and a sealer angle mounted on the top edge of said door; door closure means comprising a plurality of vertically spaced latch assemblies pivotally mounted on said door angle guides, said latch assemblies being provided with cam surfaces for engaging said rollers mounted on said door as said door is lowered into the closed position, and spring means for'yieldingly maintaining the cam surfaces of said latch assemblies in a normal camming position whereat said `cam surfaces are operative to cam said sealer angles mounted on the side walls of said door into tight pressure engagement with the adjacent surfaces of said door angle guides and to ca m said sealer angle mounted on the top edge of said door into tight pressure engagement with the adjacent end Wall of said oven as the bottom edge of said door comes into tight engagement with said door sill, said spring means also being operative to permit outward movement of said door away from said oven when a predetermined pressure level is reached within said oven.

2. The combination of claim 1, wherein said spring means is also operative yieldingly to urge said latch assemblies out of engagement with said door during movement of said door away from said oven as aforesaid.

door opening and a vertically movable door for such opening, door closure means for releasably urging said 1 door into sealing engagement with said oven adjacent said open-ing comprising a plurality of door engaging latch means, and spring means for resiliently mounting ,said

door engaging latch means adjacent the door opening in` said oven, said spring means being operative yieldingly to maintain said door engaging latch means in such a` position that vas the door is lowered into the closed position, said door will engage said latch means and be forced into sealing engagement with said oven, said spring means also being operative to permit outward movement of said door away from said oven when a predetermined pressure level is reached within said oven so as to preclude an excessive build up of pressure .therewithirn each of said door engaging latch means having a cam surface which is operative to cam said door into tight engagement with said oven when said door reaches its lowermost position, said door engaging latch means being provided with an adjustable stopper bolt fore engagement with said oven when said cam surface is in a desired camming position.

5. In combination with an industrial oven having a pressure angle mounted thereon, a door opening and a vertically movable door for such opening; door closure means for releasably urging said door into scaling engagement with said oven adjacent said opening comprising a plurality of door engaging latch means, and spring means for resiliently mounting said door engaging latch means adjacent the door opening in said oven, said spring means being operative yieldingly to maintain said door engaging latch means in such a position that as the door is lowered into the closed position, said door will engage said latch means and be forced into sealing engagement with said oven, said spring means also being operative to permit outward movement of said door away from said oven when a predetermined pressure level is reached within said oven so as to preclude an excessive build up of pressure therewithin, each of said door engaging latch means having a cam surface which is operative to cam said door into tight engagement with said oven when said door reaches its lowermost position, a socket in said door engaging latch means, said spring means comprising a rod member and a compression spring disposed around said rod member, one end of said rod member being in the shape of a ball and disposed in said socket in said door engaging latch means, said pressure angle having an aperture through which the other end of said rod member extends, each of said door engaging latch means being pivotally mounted adjacent said door opening and said pressure angle being adjustably mounted on said oven, whereupon the length of the moment arm through which the force exerted by said spring means acts against said door engaging latch means may be varied by adjustment of said pressure angle.`

6. In combination, an industrial oven or the like having door openings with doors therefor and door closure means for securing said doors in position, said door closure means comprising a plurality of latch means pivotally mounted adjacent said door openings, a spring means engaging each of said latch means for yieldingly urging said latch means and thus said doors into clamping engagement with the adjacent wall surfaces of said oven as said doors are moved to the closed position, the force exerted by said spring means through said latch means against said doors being sufficient to prevent the escape of gas from said oven around the periphery of said doors, but being insufficient substantially to resist outward movement of said ydoors away from said oven should there be an excessive build up of pressure therein, said-spring means also being operative yieldingly to urge said latch means out of engagement with said door when said door is moved outwardly due to an excessive build up of pressure within said oven as aforesaid, and a pair of stop means provided on each of said latch means, one of said stop means being operative to limit the extent to which said latch means is yieldingly urged into its clamping position, and the other of said stop means being operative to limit the extent to which said latch means is yieldingly urged out of engagement with said door.

7. In combination, an industrial oven or the like having door openings with doors therefor and door closure means for securing said doors in position, said doors having rollers mounted thereon, said door closure means comprising a plurality of latch means pivotally mounted adjacent said door openings, a spring means engaging each of said latch means for yieldingly urging said latch means and thus said doors into clamping engagment with the adjacent wall surfaces of said oven as said doors are moved to the closed position, the force exerted by said spring means through said latch means against said doors being suicient to prevent the escape of gas from said oven around the periphery of said doors, but being insuilicient substantially-to resist outward movement of said doors away from said oven should there be an excessive build up of pressure therein, said latch means being provided with cam surfaces which are adapted to be engaged by said rollers mounted on said doors, said cam surfaces being operative to cam said doors into tight engagement with the adjacent wall surfaces of said oven as said doors are lowered into the closed position.

8. The combination of claim 7 wherein the disposition of said rollers on said doors and the location of said latch means on said oven wall `are such that at least part of the weight of said doors is supported by said latch rneans when said doors are in the closed position, whereby such partial weight of said doors acting in a direction toward said oven along said cam surfaces as well as the force exerted by said spring means against said latch means urges said door into tight engagement with said adjacent oven surfaces.

9. In combination with an industrial oven having a door opening and a vertically movable door for such opening, door closure means for releasably urging said door into sealing engagement with said oven adjacent said door opening comprising a plurality of door engaging latch means mounted on said oven adjacent said door opening, and spring means for resiliently maintaining said door engaging latch means in a rst position for camming said door into such sealing engagement with said oven as said door is lowered into the closed position, said spring means also being operative to permit movement of said latch means to a second position permitting outward movement of said door away from said oven in response to a predetermined pressure level within said oven so as to preclude an excessive build up of pressure therewithin.

itl. The combination of claim 9 wherein there are a pair of vertically spaced door engaging latch means mounted adjacent each side of said door opening for pivotal movement between said rst and second positions, the spacing of said door engaging latch means being such that one of said door engaging latch means is disposed adjacent each corner of said door when said door is in the closed position.

11. The combination of claim 9 wherein each of said door engaging latch means has a cam surface which is operative to cam said door into tight engagement with said oven when said door reaches its lowermost position.

12. The combination of claim 11 wherein there is a pressure angle with an aperture therein mounted on said oven and said door engaging latch means has a socket therein, said spring means comprising a rod member and a compression spring disposed around said rod member, one end of said rod member being in the shape of a ball and disposed in said socket in said door engaging latch means, the other end of said rod member extending through said aperture in said pressure angle.

13. The combination of claim 12 wherein there is an adjustable tension nut threadedly engaging one end of said rod member and a bushing slidably disposed on the other end of said rod member and seated in said aperture in said pressure angle, the ends of said spring being conned between said nut and bushing, the force exerted by said spring means against said door engaging latch means being adapted to be varied by adjusting said tension nut to vary the effective length of said compression spring.

le. In combination, an industrial oven or the like having door openings with doors therefor, and door closure means for securing said doors in position against the adjacent wall surfaces of said oven, said door closure means comprising a plurality of latch means pivotally mounted on said oven adjacent said door openings, and spring means engaging each of said latch means for yieldingly maintaining said latch means in a position forcing said doors into clamping engagement with said adjacent Wall surfaces of said oven upon movement of said doors to the closed position, the force exerted by said spring means through said latch means against said doors being sucient to prevent the escape of gasses from said oven around the periphery of said doors, but being insuiicient substantially to resist outward movement of said doors away from said oven should there be an eX- cessive build up of pressure therein.

15. The combination `of claim 14 wherein said spring means is further operative yieldingly to maintain said latch means out of engagement with said door in response to said latch means being moved out of such engagement by said door due to excessive build up of pressure within said oven as aforesaid.

References Cited by the Examiner KENNETH W. SPRAGUE, Primary Examiner.- 

1. IN COMBINATION WITH AN INDUSTRIAL OVEN HAVING AN END WALL WITH A DOOR OPENING THEREIN AND A DOOR SILL, A DOOR FOR CLOSING SUCH OPENING, DOOR ANGLE GUIDES SECURED TO SAID END WALL ADJACENT SAID DOOR OPENING, ROLLERS MOUNTED ON SAID DOOR, SEALER ANGLES MOUNTED ON THE SIDE WALLS OF SAID DOOR, AND A SEALER ANGLE MOUNTED ON THE TOP EDGE OF SAID DOOR; DOOR CLOSURE MEANS COMPRISING A PLURALITY OF VERTICALLY SPACED LATCH ASSEMBLIES PIVOTALLY MOUNTED ON SAID DOOR ANGLE GUIDES, SAID LATCH ASSEMBLIES BEING PROVIDED WITH CAM SURFACES FOR ENGAGING SAID ROLLERS MOUNTED ON SAID DOOR AS SAID DOOR IS LOWERED INTO THE CLOSED POSITION, AND SPRING MEANS FOR YIELDINGLY MAINTAINING THE CAM SURFACES OF SAID LATCH ASSEMBLIES IN A NORMAL CAMMING POSITION WHEREAT SAID CAM SURFACES ARE OPERATIVE TO CAM SAID SEALER ANGLES MOUNTED ON THE SIDE WALLS OF SAID DOOR INTO TIGHT PRESSURE ENGAGEMENT WITH THE ADJACENT SURFACES OF SAID DOOR ANGLE GUIDES AND TO CAM SAID SEALER ANGLE MOUNTED ON THE TOP EDGE OF SAID DOOR INTO TIGHT PRESSURE ENGAGEMENT WITH THE ADJACENT END WALL OF SAID OVEN AS THE BOTTOM EDGE OF SAID DOOR COMES INTO TIGHT ENGAGEMENT WITH SAID DOOR SILL, SAID SPRING MEANS ALSO BEING OPERATIVE TO PERMIT OUTWARD MOVEMENT OF SAID DOOR AWAY FROM SAID OVEN WHEN A PREDETERMINED PRESSURE LEVEL IS REACHED WITHIN SAID OVEN. 